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Open AccessArticle

Effect of Laser Ablation on Microwave Attenuation Properties of Diamond Films

1
Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
2
Institute of Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
*
Authors to whom correspondence should be addressed.
Materials 2019, 12(22), 3700; https://doi.org/10.3390/ma12223700
Received: 1 October 2019 / Revised: 5 November 2019 / Accepted: 7 November 2019 / Published: 9 November 2019
(This article belongs to the Section Carbon Materials)
Thermal conductivity is required for developing high-power microwave technology. Diamond has the highest thermal conductivity in nature. In this study, a diamond film was synthesized by microwave plasma chemical deposition, and then long and short conductive graphite fibers were introduced to the diamond films by laser ablation. The permittivity of the samples in the K-band was measured using the transmission/reflection method. The permittivity of diamond films with short graphite fibers increased. The increase in real part of permittivity can be attributed to electron polarization, and the increase in the imaginary part can be ascribed to both polarization and electrical conductivity. The diamond films with long graphite fibers exhibited a highly pronounced anisotropy for microwave. The calculation of microwave absorption shows that reflection loss values exceeding −10 dB can be obtained in the frequency range of 21.3–23.5 GHz when the graphite fiber length is 0.7 mm and the sample thickness is 2.5 mm. Therefore, diamond films can be developed into a microwave attenuation material with extremely high thermal conductivity. View Full-Text
Keywords: diamond films; laser ablation; permittivity; microwave attenuation; high thermal conductivity diamond films; laser ablation; permittivity; microwave attenuation; high thermal conductivity
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MDPI and ACS Style

Ding, M.; Liu, Y.; Lu, X.; Tang, W. Effect of Laser Ablation on Microwave Attenuation Properties of Diamond Films. Materials 2019, 12, 3700.

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